Roquefortine C is a mycotoxin that belongs to a class of naturally occurring 2,5-diketopiperazines[1] produced by various fungi, particularly species from the genus Penicillium.

[2] It was first isolated from a strain of Penicillium roqueforti, a species commercially used as a source of proteolytic and lipolytic enzymes during maturation of the blue-veined cheeses, Roquefort, Danish Blue, Stilton and Gorgonzola.

Roquefortine C is a cyclodipeptide mycotoxin derived from the diketopiperazine cyclo(Trp-dehydro-His) and is a relatively common fungal metabolite produced by a number of Penicillium species.

[4] Although it is a potent neurotoxin[5][6] at high doses, at low concentrations of 0.05 to 1.47 mg/kg that occur in domestic cheeses, it was found to be "safe for the consumer".

[4] In addition to these toxic properties, roquefortine C reportedly possesses bacteriostatic activity against gram-positive bacteria,[8] but only in those organisms containing haemoproteins.